Major earthquakes can topple buildings, cause landslides and spawn tsunamis. Now scientists say they can do something else: set off the release of methane gas from the seabed. In a study published online Sunday in the journal Nature Geoscience, European researchers report that an underwater quake off Pakistan nearly 70 years ago likely fractured seafloor sediments and created pathways for methane, a potent greenhouse gas, to bubble up from below. The researchers say the phenomenon may be widespread enough that climate scientists should take it into account when estimating the amounts of heat-trapping gases in the atmosphere. “We suggest there is a new source that they might want to consider in the future,” said David Fischer, a postdoctoral researcher at the University of Bremen in Germany and the lead author of the study.
Methane, which is formed by the decomposition of organic material, seeps from reservoirs under the seafloor in many places around the world. But under certain conditions it mixes with seawater to form icy compounds, called gas hydrates, in the top layers of sediments. The hydrates act almost like cement, creating a barrier that prevents more free methane from coming up from below. http://www.nytimes.com/2013/07/30/scien ... .html?_r=1&

Hang on a mo ??? Methane from man made disasters and fracking don't matter but natural methane release is a threat?